Modulation of gene expression holds enormous potential for a new era in human medicine. These methodologies will allow treatment for conditions that heretofore have not been addressable by standard medical practice.
Recombinant transcription factors comprising the DNA binding domains from zinc finger proteins (“ZFPs”), TAL-effector domains (“TALEs”) and CRISPR/Cas transcription factor systems have the ability to regulate gene expression of endogenous genes (see, e.g., U.S. Pat. Nos. 8,586,526; 6,534,261; 6,599,692; 6,503,717; 6,689,558; 7,067,317; 7,262,054; Perez-Pinera et al. (2013) Nature Methods 10:973-976; Platek et al. (2014) Plant Biotechnology J. doi: 10.1111/pbi.12284). Clinical trials using these engineered transcription factors containing zinc finger proteins have shown that these novel transcription factors are capable of treating various conditions. (see, e.g., Yu et al. (2006) FASEB J. 20:479-481).
In addition, artificial nucleases comprising the DNA binding domains from zinc finger proteins (“ZFPs”), TAL-effector domains (“TALEs”), Ttago and CRISPR/Cas nuclease systems (including Cas and/or Cfp1) have the ability to modify gene expression of endogenous genes via nuclease-mediated modification of the gene, including either homology directed repair (HDR), following non-homologous end joining (NHEJ) and/or by end capture during non-homologous end joining (NHEJ) driven processes. See, for example, U.S. Pat. Nos. 9,255,250; 9,200,266; 9,045,763; 9,005,973; 9,150,847; 8,956,828; 8,945,868; 8,703,489; 8,586,526; 6,534,261; 6,599,692; 6,503,717; 6,689,558; 7,067,317; 7,262,054; 7,888,121; 7,972,854; 7,914,796; 7,951,925; 8,110,379; 8,409,861; U.S. Patent Publications 20030232410; 20050208489; 20050026157; 20050064474; 20060063231; 20080159996; 201000218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983; 20130196373; 20150056705, the disclosures of which are incorporated by reference in their entireties for all purposes. Thus, these methods often involve the use of engineered cleavage systems to induce a double strand break (DSB) or a nick in a target DNA sequence such that repair of the break by an error born process such as non-homologous end joining (NHEJ) or repair using a repair template (homology directed repair or HDR) can result in the knock out of a gene or the insertion of a sequence of interest (targeted integration). Introduction of a double strand break in the absence of an externally supplied repair template (e.g. “donor” or “transgene”) is commonly used for the inactivation of the targeted gene via mutations (insertions and/or deletions known as “indels”) introduced by the cellular NHEJ pathway.
The efficiency of transcription factor/nuclease activity can be influenced by a variety of factors such as accessibility of the target and the quality of the binding interaction between the TF or nuclease and its target nucleic acid. U.S. Pat. No. 8,772,008 describes the use of cold-shock conditions to increase nuclease activity.
However, there remains a need for additional compositions and methods for increasing activity of transgenes (e.g., nuclease, donor transgene or transcription factor) to allow for more efficient use of these powerful tools.